Current measurement method based on planar Rogowski coil current sensor and planar Rogowski coil current sensor

Abstract

The invention discloses a current measurement method based on a plane Rogowski coil current sensor and the plane Rogowski coil current sensor, and the method comprises the steps: enabling a plane Rogowski coil group to generate a coil voltage signal based on the induced electromotive force generated by a measured current when the measured current passes through a measured wire, and enabling the coil voltage signal to be transmitted to a current sensor; the coil voltage signal is input to the integrator, and the number of turns of the coil of the planar Rogowski coil assembly is jointly determined based on the sensitivity of the sensor and the bandwidth of the sensor; after receiving the coil voltage signal, the integrator performs integral operation on the coil voltage signal based on a main integral circuit in the integrator, and outputs an integral processing signal; and outputting an error compensation signal based on a compensation circuit in the integrator, and the integrator inputs the integration processing signal and the error compensation signal into a subtraction circuit in the integrator, the subtraction circuit carries out subtraction operation on the integration processing signal and the error compensation signal, a target voltage signal is output, and the detected current is determined based on the target voltage signal.

Description

Technical Field

[0001] The present application relates to the fields of current detection, high-bandwidth current sensors and power electronics technology, and in particular to a current measurement method based on a planar Rogowski coil current sensor and a planar Rogowski coil current sensor. Background Art

[0002] To ensure reliable and stable operation of power electronic converters, real-time monitoring of converter status information, including current, voltage, and temperature, is essential. Current signals, as key parameters, are often used in critical processes such as closed-loop control, condition monitoring, and fault protection. Therefore, accurate measurement of current signals is crucial for improving converter performance and ensuring reliability. With the continuous increase in switching frequency and power density, converter systems are placing higher demands on the bandwidth and integration capabilities of current sensors. In recent years, the development of high-performance current sensors that combine high bandwidth, low intrusion, strong anti-interference capabilities, and a small footprint has become a research hotspot for scholars both domestically and internationally.

[0003] Existing current measurement methods can be roughly divided into direct and indirect measurement methods based on the current measurement method. Direct measurement methods have a simple structure, and the most common one is the shunt method. However, shunts are large and cannot meet the "small size" requirement. They are also expensive and cannot provide isolation, which has limitations in practical applications. Indirect measurement methods such as electromagnetic current transformers and Hall effect current sensors have the advantage of non-contact measurement. However, although current transformers are technologically mature and highly accurate, they are bulky and expensive when measuring large currents. They are also prone to saturation and have a narrow frequency band, which cannot meet the requirements of "small size" and "high bandwidth". Hall effect current sensors can measure DC currents of hundreds of amperes, but are easily interfered by external magnetic fields, and the temperature drift of the Hall element can cause measurement errors. Their bandwidth is usually less than 1MHz, which cannot meet the "high bandwidth" requirement. Summary of the Invention

[0004] In view of this, the present application provides a current measurement method based on a planar Rogowski coil current sensor and a planar Rogowski coil current sensor. By replacing the traditional coil with a planar Rogowski coil, the advantages of low cost, small size and easy integration are fully utilized. Since no iron core is used, the Rogowski coil will not saturate and has a wide measurement range, good linearity and high precision. In addition, by seeking a balance between sensor sensitivity and sensor bandwidth, the contradiction of "high sensitivity-high bandwidth" of traditional coils is solved, and high-frequency, high-precision and anti-interference current measurement is achieved. By designing an integrator including a compensation circuit and a subtraction circuit, the compensation circuit and the subtraction circuit are used to compensate for the drift error generated by the main integration circuit, thereby improving the measurement accuracy of the planar Rogowski coil current sensor.

[0005] According to one aspect of the present application, a current measurement method based on a planar Rogowski coil current sensor is provided. The planar Rogowski coil current sensor includes a planar Rogowski coil group and an integrator. The method includes:

[0006] When the measured current passes through the measured conductor, the planar Rogowski coil assembly generates a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current, and inputs the coil voltage signal into the integrator, wherein the number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth;

[0007] After receiving the coil voltage signal, the integrator performs an integration operation on the coil voltage signal based on a main integration circuit in the integrator and outputs an integration processing signal; and outputs an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure;

[0008] The integrator inputs the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, performs a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and outputs a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

[0009] According to another aspect of the present application, a planar Rogowski coil current sensor is provided, the planar Rogowski coil current sensor comprising a planar Rogowski coil group and an integrator;

[0010] The planar Rogowski coil assembly is configured to generate a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current when the measured current passes through the measured conductor, and input the coil voltage signal into the integrator, wherein the number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth;

[0011] The integrator is configured to, after receiving the coil voltage signal, perform an integration operation on the coil voltage signal based on a main integration circuit in the integrator and output an integration processing signal; and output an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure;

[0012] The integrator is further configured to input the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, perform a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and output a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

[0013] According to another aspect of the present application, a storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the current measurement method based on the planar Rogowski coil current sensor is implemented.

[0014] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the program, the current measurement method based on the planar Rogowski coil current sensor is implemented.

[0015] By means of the above technical solution, the present application provides a current measurement method based on a planar Rogowski coil current sensor and a planar Rogowski coil current sensor. The planar Rogowski coil replaces the traditional coil, fully utilizing its advantages of low cost, small size and easy integration. Since no iron core is used, the Rogowski coil will not saturate and has a wide measurement range, good linearity and high precision. In addition, by seeking a balance between sensor sensitivity and sensor bandwidth, the contradiction of "high sensitivity-high bandwidth" of traditional coils is solved, and high-frequency, high-precision and anti-interference current measurement is achieved. By designing an integrator including a compensation circuit and a subtraction circuit, the compensation circuit and the subtraction circuit are used to compensate for the drift error generated by the main integration circuit, thereby improving the measurement accuracy of the planar Rogowski coil current sensor.

[0016] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0018] Figure 1 A schematic diagram of a flow chart of a current measurement method based on a planar Rogowski coil current sensor provided in an embodiment of the present application is shown;

[0019] Figure 2 A schematic diagram of a planar Rogowski coil current sensor provided in an embodiment of the present application is shown;

[0020] Figure 3 A schematic diagram of a process for determining the final number of turns of a planar Rogowski coil assembly provided in an embodiment of the present application is shown;

[0021] Figure 4A schematic diagram of a planar Rogowski coil assembly provided in an embodiment of the present application is shown;

[0022] Figure 5 A schematic diagram showing a lumped equivalent circuit of a planar Rogowski coil assembly provided in an embodiment of the present application is shown;

[0023] Figure 6 A schematic diagram of a two-turn planar Rogowski coil provided in an embodiment of the present application is shown;

[0024] Figure 7 A schematic diagram of two parallel wires provided in an embodiment of the present application is shown;

[0025] Figure 8 A schematic diagram of parasitic capacitance of a planar Rogowski coil assembly provided in an embodiment of the present application is shown;

[0026] Figure 9 A schematic diagram of the structure of an integrator provided in an embodiment of the present application is shown;

[0027] Figure 10 A waveform diagram of an integrator provided in an embodiment of the present application is shown;

[0028] Figure 11 A schematic diagram showing the frequency characteristics of a planar Rogowski coil assembly provided in an embodiment of the present application is shown;

[0029] Figure 12 A schematic diagram of a measured current waveform obtained by simulating a planar Rogowski coil current sensor provided in an embodiment of the present application is shown;

[0030] Figure 13 A schematic diagram of a measured current waveform obtained by measuring a planar Rogowski coil current sensor provided in an embodiment of the present application is shown;

[0031] Figure 14 A schematic diagram showing details of a measured current waveform obtained by simulation according to an embodiment of the present application is shown;

[0032] Figure 15 A schematic diagram showing details of a measured current waveform obtained by measurement according to an embodiment of the present application is shown;

[0033] Figure 16 A schematic structural diagram of a planar Rogowski coil current sensor provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0034] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0035] In this embodiment, a current measurement method based on a planar Rogowski coil current sensor is provided. The planar Rogowski coil current sensor includes a planar Rogowski coil group and an integrator. Figure 1 As shown, the method includes:

[0036] Step 101: When a measured current passes through a measured conductor, the planar Rogowski coil assembly generates a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current, and inputs the coil voltage signal into the integrator. The number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth.

[0037] Step 102: After receiving the coil voltage signal, the integrator performs an integration operation on the coil voltage signal based on a main integration circuit in the integrator and outputs an integration processing signal; and outputs an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure.

[0038] In step 103, the integrator inputs the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, performs a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and outputs a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

[0039] A current measurement method provided in an embodiment of the present application is implemented based on a planar Rogowski coil current sensor and is used to measure the current of the conductor under test. The planar Rogowski coil current sensor mainly consists of two parts, namely a planar Rogowski coil group and an integrator. When the measured current passes through the conductor under test, an alternating magnetic field is generated around it due to the change in current. The planar Rogowski coil group converts the change in magnetic flux into an induced electromotive force (i.e., the voltage signal at both ends of the coil) through magnetic field coupling. At this time, the coil voltage signal output by the planar Rogowski coil group is proportional to the rate of change of the measured current. That is, the faster the measured current changes, the greater the amplitude of the output coil voltage signal. As Figure 2 As shown, a planar Rogowski coil current sensor provided in an embodiment of the present application is shown, wherein the planar coil in the figure is the planar Rogowski coil group in the embodiment of the present application, and the integration circuit is the main integration circuit in the embodiment of the present application (the compensation circuit and the subtraction circuit are not shown).

[0040] For a planar Rogowski coil group, the number of coil turns determines the sensitivity (sensitivity) of the current sensor to changes in the measured current. The more coil turns there are, the stronger the induced electromotive force is, but at the same time the parasitic parameters of the coil (such as parasitic capacitance and parasitic inductance) will increase, resulting in a decrease in the responsiveness of the current sensor to high-frequency signals (the bandwidth becomes narrower). Therefore, when designing, it is necessary to select a suitable number of coil turns according to the application scenario (such as high-frequency switching power supply or low-frequency motor control) to ensure that the sensitivity is sufficient to detect the measured current and that the bandwidth can cover the frequency range of the signal. In addition, the use of a planar coil structure (such as a PCB winding) in this application can reduce parasitic parameters. Compared with traditional cylindrical coils, planar coils can achieve higher bandwidths at the same number of turns, or improve sensitivity at the same bandwidth, thereby optimizing the overall performance of the sensor.

[0041] Since the coil voltage signal output by the planar Rogowski coil assembly is a differential signal of the measured current (i.e., reflecting the rate of change of the measured current), what is needed in practical applications is the measured current itself (or a signal proportional to the measured current). Therefore, it is necessary to restore the differential signal to a current signal corresponding to the measured current through an integration operation. Therefore, the planar Rogowski coil current sensor in the embodiment of the present application is provided with an integrator. Here, the integrator mainly consists of three parts: a main integration circuit, an error compensation circuit, and a subtraction circuit. The main integration circuit in the integrator performs an integration operation on the coil voltage signal, converting it into a voltage signal proportional to the measured current, i.e., an integrated processing signal. The core of the integration circuit is to convert the differential characteristics of the input signal into an integral characteristic through a combination of capacitors and resistors. However, in actual integration circuits, factors such as the offset voltage of the operational amplifier, temperature drift, and the voltage drop of the coil resistance can cause errors in the integrated output, such as DC offset or gain drift. These errors accumulate over time, affecting the long-term stability of the measurement. To eliminate the errors of the main integration circuit, the embodiment of the present application designs a compensation circuit in the integrator with the same structure as the main integration circuit. The compensation circuit simulates the error characteristics of the main integrator circuit to generate an error compensation signal that matches the error component. The error compensation signal output by the compensation circuit reflects the errors of the main integrator circuit (such as gain changes caused by DC offset or temperature drift). Through a subsequent subtraction operation, these errors can be offset from the integrated processing signal. Specifically, the integrator can input the integrated processing signal output by the main integrator circuit and the error compensation signal output by the compensation circuit into the subtraction circuit. The subtraction circuit subtracts these two signals to obtain a target voltage signal. Through the subtraction operation, the long-term drift and low-frequency noise of the main integrator circuit are eliminated from the target voltage signal, thereby improving the stability and accuracy of the measurement.

[0042] The target voltage signal is proportional to the measured current, so subsequent calibration or calibration can establish a corresponding relationship between the target voltage signal and the measured current (such as a proportionality coefficient). In actual measurements, the current in the measured conductor can be determined by measuring the amplitude of the target voltage signal and combining it with the calibration parameters.

[0043] By applying the technical solution of this embodiment, a planar Rogowski coil is used instead of a traditional coil, fully utilizing its advantages of low cost, small size, and ease of integration. Since no iron core is used, the Rogowski coil will not saturate and has a wide measurement range, good linearity, and high precision. In addition, by seeking a balance between sensor sensitivity and sensor bandwidth, the "high sensitivity-high bandwidth" contradiction of traditional coils is resolved, and high-frequency, high-precision, and anti-interference current measurement is achieved. By designing an integrator including a compensation circuit and a subtraction circuit, the compensation circuit and the subtraction circuit are used to compensate for the drift error generated by the main integration circuit, thereby improving the measurement accuracy of the planar Rogowski coil current sensor.

[0044] In an embodiment of the present application, optionally, the sensor sensitivity is in direct proportion to the number of coil turns, and the sensor bandwidth is determined based on the resonant frequency of the planar Rogowski coil group; before step 101, the method further includes: initializing the coil parameters of the planar Rogowski coil group, setting the upper limit value of the measurement frequency of the planar Rogowski coil group, and the maximum and minimum values of the number of coil turns of the planar Rogowski coil group, and setting the current number of coil turns to the maximum value; when the number of coil turns of the planar Rogowski coil group is the current number of coil turns, determining the target parameter value corresponding to the coil parameter based on the coil parameters, as well as the parasitic inductance calculation formula and the parasitic capacitance calculation formula of the planar Rogowski coil group, and calculating the parasitic inductance according to the parasitic inductance calculation formula. The parasitic inductance and parasitic capacitance of the planar Rogowski coil group are calculated using the formula, the parasitic capacitance calculation formula, and the target parameter value, and the resonant frequency of the planar Rogowski coil group is calculated based on the parasitic inductance and the parasitic capacitance; whether the resonant frequency is greater than or equal to a preset multiple of the upper limit value of the measurement frequency is determined; if the determination result is negative, the current number of coil turns is reduced by a preset amount, and the resonant frequency corresponding to the planar Rogowski coil group is recalculated based on the updated current number of coil turns; if the determination result is positive, and the current number of coil turns is greater than or equal to the minimum value, the current number of coil turns is used as the final number of turns of the planar Rogowski coil group, so as to manufacture the planar Rogowski coil group of the planar Rogowski coil current sensor based on the final number of turns.

[0045] In this embodiment, the self-inductance of the planar Rogowski coil resonates with the parasitic capacitance, limiting the sensor's bandwidth. Therefore, to increase bandwidth, the number of coil turns must be reduced. However, to improve sensitivity, the number of coil turns must be increased to increase the mutual inductance of the planar Rogowski coil. Therefore, the design goal of the planar Rogowski coil assembly is to maximize sensor sensitivity while meeting the measurement bandwidth requirements.

[0046] Specifically, the coil parameters of the planar Rogowski coil assembly can be initialized. These coil parameters can include the length of each turn in the planar Rogowski coil assembly and the width of the wires in the planar Rogowski coil assembly on the printed circuit board. Furthermore, the maximum and minimum number of turns in the planar Rogowski coil assembly can be set, and the current number of turns in the planar Rogowski coil assembly can be initialized to the maximum values.

[0047] Because different numbers of coil turns correspond to different structures of planar Rogowski coil assemblies, the target parameter values corresponding to the aforementioned different coil parameters are also different. Furthermore, the formulas for calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil assembly are also different. Therefore, when the current number of coil turns is at its maximum, you can first determine the target parameter values corresponding to each coil parameter, as well as the parasitic inductance and parasitic capacitance calculation formulas for the current planar Rogowski coil assembly structure. Subsequently, based on the parasitic inductance and capacitance calculation formulas and the target parameter values, you can calculate the parasitic inductance and parasitic capacitance of the planar Rogowski coil assembly. Then, based on the parasitic inductance and parasitic capacitance, you can calculate the resonant frequency of the planar Rogowski coil assembly.

[0048] Furthermore, the magnitude relationship between the resonant frequency and a preset multiple of the upper limit value of the measurement frequency is determined. In a specific embodiment, in order to accurately detect high-frequency current, the resonant frequency f is at least higher than the upper limit value of the measurement frequency f. H Three times, so we can use f≥4f H As a condition, determine whether the current number of coil turns meets the requirements.

[0049] If it is determined that the resonant frequency is less than a preset multiple of the upper limit of the measurement frequency, the current number of coil turns may be reduced by a preset number (e.g., 1). Based on the updated current number of coil turns, the target parameter values of each coil parameter, as well as the parasitic inductance and parasitic capacitance calculation formulas of the planar Rogowski coil group, are re-determined. The resonant frequency corresponding to the planar Rogowski coil group is then calculated again.

[0050] If it is determined that the resonant frequency is greater than or equal to a preset multiple of the upper limit of the measurement frequency, and the current number of coil turns is greater than or equal to the set minimum value, then the current number of coil turns can be used as the final number of turns of the planar Rogowski coil assembly. The planar Rogowski coil assembly is subsequently manufactured based on this final number of turns to achieve a balance between sensor bandwidth and sensor sensitivity.

[0051] In a specific embodiment, the flow chart for determining the number of turns of the planar Rogowski coil group is as follows: Figure 3 As shown, the following steps are included:

[0052] 1. Initialize the coil parameters, including the shortest distance between the measured wire and each turn of the planar Rogowski coil group, the width of each turn of the planar Rogowski coil group, the length of each turn of the planar Rogowski coil group, and the trace width of the wire in the planar Rogowski coil group on the printed circuit board; set the upper limit value f of the measurement frequency of the planar Rogowski coil group H ; Set the maximum number of coil turns N max and minimum value N min , and initialize the current number of coil turns N to N max .

[0053] 2. Determine the target parameter values corresponding to the coil parameters at the current number of coil turns, as well as the parasitic inductance and capacitance calculation formulas for the planar Rogowski coil group, and calculate the parasitic inductance and capacitance of the planar Rogowski coil group at the current number of coil turns.

[0054] 3. Calculate the resonant frequency f of the planar Rogowski coil group based on the parasitic inductance and parasitic capacitance.

[0055] 4. In order to accurately detect high-frequency current, the resonant frequency f must be at least higher than f H So, f≥4f H As a condition, determine whether the current number of coil turns meets the design requirements.

[0056] 5. If the current number of coil turns does not meet the requirement of f≥4f H , then N = N-1, and execute steps 2-4 until N = N min .

[0057] 6. If the current coil structure design meets f≥4f H , then the cycle ends and the final number of turns is obtained.

[0058] According to this process, a planar Rogowski coil group that meets the bandwidth requirements and has the highest sensitivity can be obtained.

[0059] In an embodiment of the present application, optionally, the coil parameters include the length of each turn of the coil in the planar Rogowski coil group and the routing width of the wire in the planar Rogowski coil group on the printed circuit board; the “calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula and the target parameter value, and calculating the resonant frequency of the planar Rogowski coil group according to the parasitic inductance and the parasitic capacitance” includes: calculating the parasitic inductance according to the parasitic inductance calculation formula, the first parameter value corresponding to the length of each turn of the coil in the planar Rogowski coil group, the planar The parasitic inductance of the planar Rogowski coil group is calculated based on a second parameter value corresponding to a routing width of a wire in the Rogowski coil group on a printed circuit board, wherein the target parameter value includes the first parameter value and the second parameter value. The total coil length of the planar Rogowski coil group is calculated based on the first parameter value corresponding to the length of each turn of the coil in the planar Rogowski coil group, and the parasitic capacitance of the planar Rogowski coil group is calculated based on the parasitic capacitance calculation formula, the total coil length, and the second parameter value. The resonant frequency of the planar Rogowski coil group is calculated based on the parasitic inductance and parasitic capacitance.

[0060] In this embodiment, the coil parameters may include the length of each turn of the planar Rogowski coil group, the width of the wires in the planar Rogowski coil group on the printed circuit board, and the like.

[0061] In a specific embodiment, Figure 4 As shown, a planar Rogowski coil group is shown. In the present case, d is the shortest distance between the measured conductor and the outermost coil of the planar Rogowski coil group; w coil is the width of the outermost coil in the planar Rogowski coil group; l coil w is the length of the outermost coil in the planar Rogowski coil group; wind is the trace width of the conductor on the printed circuit board (PCB) in the planar Rogowski coil group; S is the winding gap. The lumped parameter model of the planar Rogowski coil group is as follows: Figure 5 As shown, M is the mutual inductance between the measured conductor and the planar Rogowski coil group; L is the self-inductance of the planar Rogowski coil group; R is the parasitic resistance of the planar Rogowski coil group; C is the parasitic capacitance of the planar Rogowski coil group; R s is the damping resistance of the planar Rogowski coil group (small and negligible).

[0062] Among them, the parasitic inductance L directly affects the bandwidth of the planar Rogowski coil group. To achieve high bandwidth, L needs to be reduced as much as possible. Figure 6 As shown, the parasitic inductance L is composed of the self-inductance L of each wire segment. i , and the mutual inductance M between the two wires i,jJoint decision. Figure 6 Taking the planar Rogowski coil group of this structure as an example, the calculation formula of parasitic inductance is as follows:

[0063]

[0064] Where L0 is the self-inductance of all conductors. + is positive mutual inductance, M - is the negative mutual inductance. The self-inductance of the PCB trace can be calculated according to (2). Where t is the thickness of the conductor (the thickness of the copper trace used for the PCB trace).

[0065]

[0066] Among them, l coil,i is the length of the i-th coil.

[0067] like Figure 7 As shown in the figure, taking two parallel conductors as an example, the calculation method of mutual inductance is explained.

[0068] Figure 7 The mutual inductance between the two conductors is given by:

[0069]

[0070] The calculation of the mutual inductance of each trace is as follows:

[0071]

[0072] Among them, D x is the geometric distance between the two conductors (e.g. Figure 7 D), l coil,x The subscript x corresponds to the length of the conductor. For example, l coil,m The subscript m corresponds to the length of the conductor, l coil,m+q It is the sum of the length of the conductor corresponding to the subscript m and the length of the conductor corresponding to the subscript q.

[0073] like Figure 2 and 8 As shown, the parasitic capacitance of the planar Rogowski coil group is the substrate capacitance C sub The overlap capacitance C generated by the overlap between the top and bottom conductors of the coil over The sum is calculated as follows:

[0074]

[0075] Where, ε is the relative dielectric constant of FR-4, l coil,all is the sum of the lengths of the turns of the planar Rogowski coil group (i.e. the total length of the coil), S overis the overlap area between the top and bottom traces, t FR4 is the thickness of FR-4.

[0076] In addition, the resonant frequency is calculated as:

[0077]

[0078] In an embodiment of the present application, optionally, the main integration circuit includes a first resistor R1, a second resistor R2, a first capacitor C1, a second capacitor C2, a first operational amplifier OP1 and a reset switch S; the first end of the first resistor R1 is connected to the output end of the planar Rogowski coil group, the second end of the first resistor R1 is respectively connected to the first end of the first capacitor C1 and the non-inverting input end of the first operational amplifier OP1, the second end of the first capacitor C1 is respectively connected to the ground end and the first end of the second resistor R2, the second end of the second resistor R2 is respectively connected to the inverting input end of the first operational amplifier OP1, the first end of the second capacitor C2 and the first end of the reset switch S, and the output end of the first operational amplifier OP1 is respectively connected to the second end of the second capacitor C2 and the second end of the reset switch S.

[0079] In an embodiment of the present application, optionally, the compensation circuit includes the first resistor R1, the second resistor R2, the first capacitor C1, the second capacitor C2, the first operational amplifier OP1 and the reset switch S; the first end of the first resistor R1 is respectively connected to the first end of the first capacitor C1 and the non-inverting input end of the first operational amplifier OP1, the second end of the first resistor R1 is respectively connected to the second end of the first capacitor C1, the ground end and the first end of the second resistor R2, the second end of the second resistor R2 is respectively connected to the inverting input end of the first operational amplifier OP1, the first end of the second capacitor C2 and the first end of the reset switch S, and the output end of the first operational amplifier OP1 is respectively connected to the second end of the second capacitor C2 and the second end of the reset switch S.

[0080] In an embodiment of the present application, optionally, the subtraction circuit includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6 and a second operational amplifier OP2; the first end of the third resistor R3 is connected to the output end of the first operational amplifier OP1 in the main integration circuit, the second end of the third resistor R3 is respectively connected to the first end of the fourth resistor R4 and the non-inverting input end of the second operational amplifier OP2, and the second end of the fourth resistor R4 is connected to the ground end; the first end of the fifth resistor R5 is connected to the output end of the first operational amplifier OP1 in the compensation circuit, the second end of the fifth resistor R5 is respectively connected to the first end of the sixth resistor R6 and the inverting input end of the second operational amplifier OP2, and the second end of the sixth resistor R6 is connected to the output end of the second operational amplifier OP2.

[0081] In an embodiment of the present application, optionally, the method further includes: when the measured conductor starts working, controlling the reset switches in the main integration circuit and the compensation circuit to be disconnected; when the measured conductor stops working, controlling the reset switches in the main integration circuit and the compensation circuit to be closed.

[0082] In this embodiment, Figure 9 As shown in FIG, an integrator provided by an embodiment of the present application is shown, wherein the integrator includes a main integration circuit, a subtraction circuit and a compensation circuit. The coil voltage signal outputted from the output end of the planar Rogowski coil group is V coil (t), the output of the first operational amplifier OP1 of the main integration circuit corresponds to the output integration processing signal V' out (t)+V err The error compensation signal outputted from the output terminal of the first operational amplifier OP1 of the compensation circuit is V′ err The target voltage signal outputted from the output terminal of the second operational amplifier OP2 of the subtraction circuit is V out (t).

[0083] According to Lenz's law, the coil voltage signal of the planar Rogowski coil group is proportional to the measured current I m Therefore, in order to reconstruct I m The waveform of the sensor must be connected to the back end of the planar Rogowski coil group. The calculation formula for the sensor output voltage is:

[0084]

[0085] Among them, k I is the integration coefficient, G th is the sensitivity. Figure 9As shown in Figure 1, the integration circuit used in this current sensor consists of three parts, including the main integration circuit, the compensation circuit, and the subtraction circuit. For the main integration circuit, the offset voltage and offset current on the input side of the first operational amplifier continuously charge the integration capacitor, resulting in a drift error V at the output of the first operational amplifier. err , as shown in formula (8). The drift error in the pure integration circuit will gradually accumulate over time, manifesting as the measured current signal continuously shifting upward until it reaches the maximum voltage that the first operational amplifier can output, eventually causing the operational amplifier to saturate and fail to operate.

[0086]

[0087] The reset switch S is used to periodically discharge the integral capacitor. Figure 10 As shown in Figure 1, when the conductor being measured is turned off, the integrator is reset to ensure that the output of the integrator always starts from zero potential. Because drift error always exists, when the main integration circuit is working, the output signal of the current sensor still has drift error. In order to effectively solve this problem, as shown in Figure 1, Figure 9 As shown, a compensation circuit and subtraction circuit are used. The structure and parameters of the compensation circuit are basically the same as those of the main integration circuit, so the drift errors output by the two circuits are basically the same. When the reset switch S is disconnected, the output of the compensation circuit is the drift voltage V err .like Figure 10 As shown, by using a subtraction circuit to subtract the output of the main integration circuit from the output of the compensation circuit, the drift error can be eliminated, thereby effectively improving the accuracy of current measurement.

[0088] In a specific embodiment, the design and simulation of the planar Rogowski coil current sensor are verified. The frequency characteristics of the planar Rogowski coil group are as follows: Figure 11 It can be clearly seen that the calculated results are basically consistent with the simulation results, which verifies the accuracy of the established model.

[0089] Next, the designed planar Rogowski coil current sensor was simulated and verified. A dual-pulse circuit was created in Ltspice to verify the current sensor's high-frequency performance. During the turn-on and turn-off cycles of a power device, the current in the power circuit changes rapidly and oscillates at high frequencies, reaching tens of MHz. Measuring the power current using the designed current sensor verifies its high-frequency performance.

[0090] Figure 12 is the current waveform flowing through the power switching device. Figure 13 is the measurement result of the current sensor. Figure 13 Comparing the measurement results of the current sensor without drift compensation with the measurement results with drift compensation, it can be clearly seen that the measurement results of the current sensor without compensation have obvious drift compared to the measurement results of the current sensor with drift compensation. Figure 12 and Figure 13 The details of the waveform are as follows Figure 14 、 Figure 15 As shown. It can be seen that even if I m The oscillation frequency is as high as 17MHz, and the current sensor can still accurately measure I m Therefore, the excellent high-frequency performance of the designed sensor and the correctness of the design method are verified by measuring the switching current oscillation waveform.

[0091] Further, as Figure 1 The specific implementation of the method, the embodiment of the present application provides a planar Rogowski coil current sensor, such as Figure 16 As shown, the planar Rogowski coil current sensor includes a planar Rogowski coil group and an integrator;

[0092] The planar Rogowski coil assembly is configured to generate a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current when the measured current passes through the measured conductor, and input the coil voltage signal into the integrator, wherein the number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth;

[0093] The integrator is configured to, after receiving the coil voltage signal, perform an integration operation on the coil voltage signal based on a main integration circuit in the integrator and output an integration processing signal; and output an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure;

[0094] The integrator is further configured to input the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, perform a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and output a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

[0095] Optionally, the sensor sensitivity is directly proportional to the number of coil turns, and the sensor bandwidth is determined based on the resonant frequency of the planar Rogowski coil assembly; and the final number of turns of the planar Rogowski coil assembly is determined based on the following method:

[0096] Initializing coil parameters of the planar Rogowski coil group, setting an upper limit value of a measurement frequency of the planar Rogowski coil group, and a maximum value and a minimum value of the number of coil turns of the planar Rogowski coil group, and setting the current number of coil turns to the maximum value;

[0097] When the number of coil turns of the planar Rogowski coil group is the current number of coil turns, determining, based on the coil parameters, target parameter values corresponding to the coil parameters, as well as a parasitic inductance calculation formula and a parasitic capacitance calculation formula of the planar Rogowski coil group; calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter values; and calculating the resonant frequency of the planar Rogowski coil group based on the parasitic inductance and the parasitic capacitance;

[0098] Determining whether the resonant frequency is greater than or equal to a preset multiple of the upper limit value of the measurement frequency;

[0099] If the judgment result is no, reducing the current number of coil turns by a preset amount, and recalculating the resonant frequency corresponding to the planar Rogowski coil group based on the updated current number of coil turns;

[0100] If the judgment result is yes, and the current number of coil turns is greater than or equal to the minimum value, the current number of coil turns is used as the final number of turns of the planar Rogowski coil assembly, so as to manufacture the planar Rogowski coil assembly of the planar Rogowski coil current sensor based on the final number of turns.

[0101] Optionally, the coil parameters include the length of each turn of the planar Rogowski coil group and the width of a wire in the planar Rogowski coil group on a printed circuit board;

[0102] Calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter value, and calculating the resonant frequency of the planar Rogowski coil group according to the parasitic inductance and the parasitic capacitance, includes:

[0103] Calculating the parasitic inductance of the planar Rogowski coil group according to the parasitic inductance calculation formula, a first parameter value corresponding to the length of each turn of the planar Rogowski coil group, and a second parameter value corresponding to the width of a wire in the planar Rogowski coil group on a printed circuit board, wherein the target parameter value includes the first parameter value and the second parameter value;

[0104] Calculating a total coil length corresponding to the planar Rogowski coil group based on a first parameter value corresponding to a length of each coil turn in the planar Rogowski coil group, and calculating a parasitic capacitance corresponding to the planar Rogowski coil group based on the parasitic capacitance calculation formula, the total coil length, and the second parameter value;

[0105] The resonant frequency corresponding to the planar Rogowski coil group is calculated according to the parasitic inductance and parasitic capacitance.

[0106] Optionally, the main integration circuit includes a first resistor, a second resistor, a first capacitor, a second capacitor, a first operational amplifier, and a reset switch;

[0107] The first end of the first resistor is connected to the output end of the planar Rogowski coil group, the second end of the first resistor is respectively connected to the first end of the first capacitor and the non-inverting input end of the first operational amplifier, the second end of the first capacitor is respectively connected to the ground end and the first end of the second resistor, the second end of the second resistor is respectively connected to the inverting input end of the first operational amplifier, the first end of the second capacitor and the first end of the reset switch, and the output end of the first operational amplifier is respectively connected to the second end of the second capacitor and the second end of the reset switch.

[0108] Optionally, the compensation circuit includes the first resistor, the second resistor, the first capacitor, the second capacitor, the first operational amplifier, and the reset switch;

[0109] The first end of the first resistor is respectively connected to the first end of the first capacitor and the non-inverting input terminal of the first operational amplifier, the second end of the first resistor is respectively connected to the second end of the first capacitor, the ground terminal and the first end of the second resistor, the second end of the second resistor is respectively connected to the inverting input terminal of the first operational amplifier, the first end of the second capacitor and the first end of the reset switch, and the output end of the first operational amplifier is respectively connected to the second end of the second capacitor and the second end of the reset switch.

[0110] Optionally, the subtraction circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a second operational amplifier;

[0111] A first end of the third resistor is connected to the output end of the first operational amplifier in the main integration circuit, a second end of the third resistor is connected to the first end of the fourth resistor and the non-inverting input end of the second operational amplifier respectively, and a second end of the fourth resistor is connected to the ground end;

[0112] The first end of the fifth resistor is connected to the output end of the first operational amplifier in the compensation circuit, the second end of the fifth resistor is respectively connected to the first end of the sixth resistor and the inverting input end of the second operational amplifier, and the second end of the sixth resistor is connected to the output end of the second operational amplifier.

[0113] Optionally, the integrator is further configured to:

[0114] When the measured wire starts to work, controlling the reset switches in the main integration circuit and the compensation circuit to be disconnected;

[0115] When the measured wire stops working, the reset switches in the main integration circuit and the compensation circuit are controlled to be closed.

[0116] It should be noted that for other corresponding descriptions of the functional units involved in the planar Rogowski coil current sensor provided in the embodiment of the present application, reference can be made to Figures 1 to 15 The corresponding description in the method will not be repeated here.

[0117] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0118] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0119] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A current measurement method based on a planar Rogowski coil current sensor, characterized in that: The planar Rogowski coil current sensor includes a planar Rogowski coil group and an integrator; the method includes: When the measured current passes through the measured conductor, the planar Rogowski coil assembly generates a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current, and inputs the coil voltage signal into the integrator, wherein the number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth; After receiving the coil voltage signal, the integrator performs an integration operation on the coil voltage signal based on a main integration circuit in the integrator and outputs an integration processing signal; and outputs an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure; The integrator inputs the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, performs a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and outputs a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

2. The method according to claim 1, characterized in that The sensor sensitivity is directly proportional to the number of coil turns, and the sensor bandwidth is determined based on the resonant frequency of the planar Rogowski coil group; Before the planar Rogowski coil group generates a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current, the method further includes: Initializing coil parameters of the planar Rogowski coil group, setting an upper limit value of a measurement frequency of the planar Rogowski coil group, and a maximum value and a minimum value of the number of coil turns of the planar Rogowski coil group, and setting the current number of coil turns to the maximum value; When the number of coil turns of the planar Rogowski coil group is the current number of coil turns, determining, based on the coil parameters, target parameter values corresponding to the coil parameters, as well as a parasitic inductance calculation formula and a parasitic capacitance calculation formula of the planar Rogowski coil group; calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter values; and calculating the resonant frequency of the planar Rogowski coil group based on the parasitic inductance and the parasitic capacitance; Determining whether the resonant frequency is greater than or equal to a preset multiple of the upper limit value of the measurement frequency; If the judgment result is no, reducing the current number of coil turns by a preset amount, and recalculating the resonant frequency corresponding to the planar Rogowski coil group based on the updated current number of coil turns; If the judgment result is yes, and the current number of coil turns is greater than or equal to the minimum value, the current number of coil turns is used as the final number of turns of the planar Rogowski coil assembly, so as to manufacture the planar Rogowski coil assembly of the planar Rogowski coil current sensor based on the final number of turns.

3. The method according to claim 2, characterized in that The coil parameters include the length of each turn of the planar Rogowski coil group and the width of the wires of the planar Rogowski coil group on the printed circuit board; Calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter value, and calculating the resonant frequency of the planar Rogowski coil group according to the parasitic inductance and the parasitic capacitance, includes: Calculating the parasitic inductance of the planar Rogowski coil group according to the parasitic inductance calculation formula, a first parameter value corresponding to the length of each turn of the planar Rogowski coil group, and a second parameter value corresponding to the width of a wire in the planar Rogowski coil group on a printed circuit board, wherein the target parameter value includes the first parameter value and the second parameter value; Calculating a total coil length corresponding to the planar Rogowski coil group based on a first parameter value corresponding to a length of each coil turn in the planar Rogowski coil group, and calculating a parasitic capacitance corresponding to the planar Rogowski coil group based on the parasitic capacitance calculation formula, the total coil length, and the second parameter value; The resonant frequency corresponding to the planar Rogowski coil group is calculated according to the parasitic inductance and parasitic capacitance.

4. The method according to claim 1, wherein The main integration circuit includes a first resistor, a second resistor, a first capacitor, a second capacitor, a first operational amplifier, and a reset switch; The first end of the first resistor is connected to the output end of the planar Rogowski coil group, the second end of the first resistor is respectively connected to the first end of the first capacitor and the non-inverting input end of the first operational amplifier, the second end of the first capacitor is respectively connected to the ground end and the first end of the second resistor, the second end of the second resistor is respectively connected to the inverting input end of the first operational amplifier, the first end of the second capacitor and the first end of the reset switch, and the output end of the first operational amplifier is respectively connected to the second end of the second capacitor and the second end of the reset switch.

5. The method according to claim 4, characterized in that The compensation circuit includes the first resistor, the second resistor, the first capacitor, the second capacitor, the first operational amplifier, and the reset switch; The first end of the first resistor is respectively connected to the first end of the first capacitor and the non-inverting input terminal of the first operational amplifier, the second end of the first resistor is respectively connected to the second end of the first capacitor, the ground terminal and the first end of the second resistor, the second end of the second resistor is respectively connected to the inverting input terminal of the first operational amplifier, the first end of the second capacitor and the first end of the reset switch, and the output end of the first operational amplifier is respectively connected to the second end of the second capacitor and the second end of the reset switch.

6. The method according to claim 3 or 4, characterized in that The subtraction circuit includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor and a second operational amplifier; A first end of the third resistor is connected to the output end of the first operational amplifier in the main integration circuit, a second end of the third resistor is connected to the first end of the fourth resistor and the non-inverting input end of the second operational amplifier respectively, and a second end of the fourth resistor is connected to the ground end; The first end of the fifth resistor is connected to the output end of the first operational amplifier in the compensation circuit, the second end of the fifth resistor is respectively connected to the first end of the sixth resistor and the inverting input end of the second operational amplifier, and the second end of the sixth resistor is connected to the output end of the second operational amplifier.

7. The method according to claim 6, characterized in that The method further comprises: When the measured wire starts to work, controlling the reset switches in the main integration circuit and the compensation circuit to be disconnected; When the measured wire stops working, the reset switches in the main integration circuit and the compensation circuit are controlled to be closed.

8. A planar Rogowski coil current sensor, characterized in that: The planar Rogowski coil current sensor includes a planar Rogowski coil group and an integrator; The planar Rogowski coil assembly is configured to generate a coil voltage signal corresponding to the measured current based on the induced electromotive force generated by the measured current when the measured current passes through the measured conductor, and input the coil voltage signal into the integrator, wherein the number of coil turns of the planar Rogowski coil assembly is determined based on the sensor sensitivity and the sensor bandwidth; The integrator is configured to, after receiving the coil voltage signal, perform an integration operation on the coil voltage signal based on a main integration circuit in the integrator and output an integration processing signal; and output an error compensation signal based on a compensation circuit in the integrator; wherein the main integration circuit and the compensation circuit have the same structure; The integrator is further configured to input the integrated processing signal and the error compensation signal into a subtraction circuit in the integrator, perform a subtraction operation on the integrated processing signal and the error compensation signal through the subtraction circuit, and output a target voltage signal to determine the measured current of the measured conductor based on the target voltage signal.

9. The planar Rogowski coil current sensor according to claim 8, characterized in that: The sensor sensitivity is directly proportional to the number of coil turns, and the sensor bandwidth is determined based on the resonant frequency of the planar Rogowski coil assembly. The final number of turns of the planar Rogowski coil assembly is determined based on the following method: Initializing coil parameters of the planar Rogowski coil group, setting an upper limit value of a measurement frequency of the planar Rogowski coil group, and a maximum value and a minimum value of the number of coil turns of the planar Rogowski coil group, and setting the current number of coil turns to the maximum value; When the number of coil turns of the planar Rogowski coil group is the current number of coil turns, determining, based on the coil parameters, target parameter values corresponding to the coil parameters, as well as a parasitic inductance calculation formula and a parasitic capacitance calculation formula of the planar Rogowski coil group; calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter values; and calculating the resonant frequency of the planar Rogowski coil group based on the parasitic inductance and the parasitic capacitance; Determining whether the resonant frequency is greater than or equal to a preset multiple of the upper limit value of the measurement frequency; If the judgment result is no, reducing the current number of coil turns by a preset amount, and recalculating the resonant frequency corresponding to the planar Rogowski coil group based on the updated current number of coil turns; If the judgment result is yes, and the current number of coil turns is greater than or equal to the minimum value, the current number of coil turns is used as the final number of turns of the planar Rogowski coil assembly, so as to manufacture the planar Rogowski coil assembly of the planar Rogowski coil current sensor based on the final number of turns.

10. The planar Rogowski coil current sensor according to claim 9, characterized in that: The coil parameters include the length of each turn of the planar Rogowski coil group and the width of the wires of the planar Rogowski coil group on the printed circuit board; Calculating the parasitic inductance and parasitic capacitance of the planar Rogowski coil group according to the parasitic inductance calculation formula, the parasitic capacitance calculation formula, and the target parameter value, and calculating the resonant frequency of the planar Rogowski coil group according to the parasitic inductance and the parasitic capacitance, includes: Calculating the parasitic inductance of the planar Rogowski coil group according to the parasitic inductance calculation formula, a first parameter value corresponding to the length of each turn of the planar Rogowski coil group, and a second parameter value corresponding to the width of a wire in the planar Rogowski coil group on a printed circuit board, wherein the target parameter value includes the first parameter value and the second parameter value; Calculating a total coil length corresponding to the planar Rogowski coil group based on a first parameter value corresponding to a length of each coil turn in the planar Rogowski coil group, and calculating a parasitic capacitance corresponding to the planar Rogowski coil group based on the parasitic capacitance calculation formula, the total coil length, and the second parameter value; The resonant frequency corresponding to the planar Rogowski coil group is calculated according to the parasitic inductance and parasitic capacitance.

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